Unbreak build. uint32_t is C99

Index: libobs/graphics/graphics.h
--- libobs/graphics/graphics.h.orig
+++ libobs/graphics/graphics.h
@@ -492,7 +492,7 @@ struct gs_window {
 	void *hwnd;
 #elif defined(__APPLE__)
 	__unsafe_unretained id view;
-#elif defined(__linux__) || defined(__FreeBSD__)
+#else
 	/* I'm not sure how portable defining id to uint32_t is. */
 	uint32_t id;
 	void *display;
@@ -936,7 +936,7 @@ EXPORT gs_stagesurf_t *gs_stagesurface_create_nv12(uin
 EXPORT void gs_register_loss_callbacks(const struct gs_device_loss *callbacks);
 EXPORT void gs_unregister_loss_callbacks(void *data);
 
-#elif defined(__linux__) || defined(__FreeBSD__)
+#elif defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__)
 
 EXPORT gs_texture_t *gs_texture_create_from_dmabuf(
 	unsigned int width, unsigned int height, uint32_t drm_format,
